1. Field of the Invention
The present invention relates to typefaces or fonts for typographic apparatus used in desktop publishing (DTP) and the like. More particularly, the invention relates to a kerning method for reducing facing space between characters and to a typographic apparatus utilizing this method.
2. Description of the Related Art
In arranging characters of a character string in a predetermined direction, an object character may be positionally adjusted or kerned relative to an adjacent reference character already fixed in place. An example of such kerning methods is disclosed in Japanese Patent Publication (Unexamined) No. 1975-65223. In this prior method, facing space between dot patterns of the faces of two characters is determined in a direction of character arrangement, and the characters are arranged so that the facing space produces a desired space between the faces thereof. In the methods disclosed in Japanese Patent Publications (Unexamined) Nos. 1990-243343 and 1991-269490, face outlines of two characters are scanned in a direction of character arrangement to compute space between the faces, and the characters are positioned to have a desired space between their faces.
In all of the above kerning methods, space between adjacent character faces is determined only in a direction of character arrangement. Where characters are successively arranged in a horizontal direction, for example, spacing is determined only in the horizontal direction. If an object character is placed relative to a reference character with a desired space between their faces, the two-dimensional space between the faces as seen obliquely or vertically, depending on character combinations, may be smaller than a desired space between the faces, or the faces could partly overlap each other. This impairs appearance.
In such kerning methods, after all, the operator must look at character strings on a CRT or the like and carry out fine adjustments empirically in order to adjust two-dimensional spacing including oblique and vertical directions between character faces. This process requires the operator to have a high level of skill and takes considerable time. For certain character combinations, amounts of space reduction may be determined in advance and stored in memory. However, such amounts have fixed-values and require a large storage capacity. Besides, the kerning process cannot be effected between different, size characters.
Japanese Patent Publication (Unexamined) No. 1991-244542, for example, discloses a kerning method in which characters are positioned based on two-dimensional space between their faces which is determined in oblique and vertical directions as well as a direction of character arrangement. According to this method, first of all, face dot patterns of two characters are spread by half a desired facing space. Then, the spread dot pattern of the object character is moved toward the dot pattern of the reference character. An amount of movement resulting in contact between the spread dot patterns is determined, and the object character before the spreading process is positioned by regarding the amount of movement as an amount of space reduction.
However, this method requires a time-consuming spreading process to compute an amount of movement (i.e. a space reduction amount) corresponding to a desired space between character faces. For varying the desired space between the character faces, the spreading process must be carried out all over again. Thus, although it is possible to arrange characters with desired two-dimensional spacing, this method has a disadvantage of slow processing and is unsuitable to fine adjustments of spacing between character faces involving a repetition of varied space settings.